Things that can disturb WiFi (in no particular order):
1/ Large metal objects (old steel ones) like Filing Cabinets, Radiators, Reinforced Steel Girders...
2/ Microwave ovens.
3/ DECT Phones.
4/ Wireless Video Senders.
5/ Neighbour's WiFi.
The latter is most likely to be the cause - why does every manufacturer or routers default to channel 1?
I suggest changing your channel to 7 or 11.
You need to know your router's IP address: 192.168.X.1 is most likely, with X = 0,1,2 or 123.
Then you need your Username and Password - check router manual.
Finally you need to go into the WiFi or WLAN settings and look for the Channel setting.